fix: repl erroring "let used as operator" with empty/nil inputs

this was fixed by transforming empty inputs to nil and not
transforming nil inputs to empty inputs.

1 files changed, 3 insertions, 1 deletions

diff --git a/src/main.rs b/src/main.rs
index 30bd136..d7a2196 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -191,13 +191,15 @@ fn repl(mut binds: Vec<SExp>) -> Result<(), io::Error> {
 	}
 
         let orig_expression = match parse_to_ast(&input) {
-            Ok(SCons(a, b)) if *b == Atom(Nil) => *a,
+            Ok(SCons(a, b)) if *b == Atom(Nil) && *a != Atom(Nil) => *a,
+	    Ok(Atom(Nil)) => scons(Nil, Nil),
             Ok(t) => t,
 	    Err(e) => {
 		println!("Syntax error: {}", e);
 		continue;
 	    },
         };
+
 	if let Some((name, _value)) = orig_expression.clone().check_let() {
 	    let mut expr = scons(orig_expression.clone(), scons(Nil, Nil));
 	    for i in 1..=binds.len() {